import math
r1 = float(input())/2
r2 = float(input())/2
"""
e**3 = (4/3* math.pi*(r1**3) + 4/3* math.pi*(r2**3))
"""
e = (4/3*math.pi*(r1**3) + 4/3*math.pi*(r2**3))**(1/3)
print(f"正方体边长为:{e:.2f}.")  